1. Field of the Invention
The present invention relates to the technique of an information terminal device having a display.
2. Description of the Background Art
In data communication of an information terminal device, as radio communication infrastructure develops, downloading of information via an access point such as a hot spot (radio spot) became possible also in a portable information terminal, and information terminals are connected by radio and share information.
In the case where it is difficult to supply power from an external power supply at the time of performing radio communications in a portable information terminal, power is supplied from an internal power supply such as a built-in battery. In such a case, it is important to increase the life of the battery or the like by saving power (lowering power) of radio communication. In particular, in the case of connecting information terminals in an ad-hoc mode by using a wireless LAN, it is necessary to transmit a beacon signal for recognizing the existence of a communicable terminal, so that power consumption increases.
With respect to the radio communication in the ad-hoc mode, for example, there is a power saving technique disclosed in Japanese Unexamined Patent Application Publication No. 2005-328515. According to the technique, in the case where an information terminal receives a beacon signal for a sleep mode, the information terminal enters the sleep mode. After lapse of a predetermined sleep period, each of the information terminals is activated again by a timer process, communication restarts, and the operations are repeated. By such operations, connection between information terminals is established in predetermined cycles. Consequently, the number of transmitting times of the beacon signal accompanying considerable power consumption decreases, and power saving is achieved.
In the technique of Japanese Unexamined Patent Application Publication No. 2005-328515, however, the beacon signal for establishing connection between the information terminals is transmitted periodically and, in some cases, the beacon signal is transmitted even when data communication is unnecessary. It cannot be said that power consumption is effectively made in radio communication between information terminals.